The present invention relates to a composition for dyeing keratin fibers based on vegetable dyes and direct-dyeing dye compounds and to a method of dyeing hair using this composition.
Vegetable dyes are used to an increasing extent for dyeing of keratin fibers, especially human hair, since these dyes permit a safe dyeing of keratin fibers.
The vegetable dyes are used in the form of a powder or granulate, which is mixed prior to use with water.
However several disadvantages are associated with the use of this type of vegetable dye powder and/or vegetable dye granulate, which can contain many ingredients.
Separation of component ingredients frequently occurs in vegetable dye powders or vegetable dye granulate mixtures of several granulates containing raw materials of different densities during transport or storage. The heavier ingredients sink into the lower portion while the lighter ingredients collect in the upper portion. This separation has the consequence that equal amounts of granulate or powder taken from different locations have different compositions and thus can have different dyeing properties.
In order to avoid this separation it is necessary to shake the powder or granulate prior to taking a portion of it to avoid this separation problem. However often the user does not do that.
A separation can be prevented also by use of powder mixtures with very fine grain size. This however has the disadvantage that this type of powder mixture--especially during opening of the container, removal of a portion of the powder or during mixing with water--is inclined to generate a large amount of dust.
Furthermore should, for example, vegetable granulates be used comprising granulates which are indeed dust-free and more or less compact in accordance with the method used to produce them, fine dust may still form by friction of the granulates with each other, especially during transportation.
The prepared vegetable dye slurries or pastes obtained with the above-named powders and granulates also have application-specific disadvantages. They are difficult to apply and have poor adherence to the hair. During the acting time the dye mass dries and crumbles away. The vegetable dye paste or slurry formed also has poor rinsibility.
Numerous attempts have already been made to solve this problem.
Published European Patent Application 0 630 643 (EP-OS 0 630 643) discloses producing a pourable powder by using a special granulation process with addition of waxes having a flow point of 40.degree. C. to 130.degree. C. and thus to reduce the dusting. Dusting cannot be totally avoided using this powder however, especially during transfer of the vegetable dye powder into a stirring vessel and during mixing of the vegetable dye powder with water. Furthermore depending on the employed wax the miscibility of this dye powder with water is very variable and often unsatisfactory.
An additional problem with vegetable hair dye compounds is the poor color coverage of the hair dye compositions based on them.
Although numerous attempts have been made to find hair dye compositions based on vegetable dye ingredients which overcome these problems, a satisfactory composition of this type has not been found until now.